Abstracto

Pantoscopic tilt induced higher order aberrations characterization using Shack Hartmann wave front sensor and comparison with Martin's Rule

Venkataramana Kalikivayi, Kannan K, Ganesan

Purpose: The aim of this work is to characterize the higher order aberrations due to Pantoscopic Tilt using Shack Hartmann Wave front Sensor and comparing it with Martin’s Rule. Methods: A Shack Hartmann wavefront sensor consisting of a hexagonal array of 127 micro lenses and a CCD Camera is used in this work to measure the tilt induced optical aberrations. The optical set up was aligned for perfect centration. A rotation stage was set for one of the lenses to induce pantoscopic tilt. The tilt was given from 10 to 130 in steps of 10. At each step, the various optical aberrations, consisting of first 15 Zernike terms were measured and analyzed. The resultant spherical equivalent is calculated using both methods viz., from SHWFS and Martin’s rule. Results: Pantoscopic tilt showed significant increase in 2nd and 4th order aberrations. Change in spherical equivalent of 0.50 D, 1.00 D and 2.00 D were observed for tilts of 40, 70 and 100 respectively. Whereas with Martin’s rule, the total change in the resultant spherical equivalent for 100 is 0.11 D only. The pantoscopic tilt increases 2nd and 4th order aberrations significantly and there was no statistical significant correlation for 3rd order aberrations. Conclusion: Our study insists the pantoscopic tilt induced aberrations should be taken into account while designing spectacle lenses and their frames for proper seating on the nose bridge and ears